A narrow hybrid zone between closely related cricket species.

Abstract

Although Gryllus pennsylvanicus and G. firmus differ in morphology and electromorph frequency, no single character is diagnostic. Data are presented on morphological and allozymic variation reveal an extensive zone of interaction in the eastern United States. This zone appears to follow the easternmost ridge of mountains (the Blue Ridge in Virginia, the Appalachians in Pennsylvania, New Jersey and New York). Little gene exchange occurs where the species are found together in Virginia, but significant gene exchange may occur in areas of the northeast. -from Authors